TECHNICAL FIELD
[0001] The present invention generally relates to an article of furniture, and more particularly,
to a tiltable stool or chair which self-adjusts to the weight of a user.
BACKGROUND
[0002] Articles of furniture such as stools or chairs which allow a user to rock forward,
backward and sideways are generally known. A tiltable stool is typically configured
to be used on a generally horizontal surface such as a floor. The stool comprises
a top section providing seat and a base section comprising a rounded bottom surface
configured to support the stool on the floor.
[0003] The base section may be a weighted base which has a downwardly convex lateral surface
area to support the stool upon contacting the floor when the stool is tilted out of
its normal upright position. In that normal position the stool rests on the floor
with a flat or concave area of its base. The weighting of the base is so chosen that
the center of gravity of the stool comes to lie inwardly of the perimeter of the central
contact area in its tilted state. The support areas may be contiguous, thus forming
part of a continuous annular surface, or may be peripherally spaced apart, as by being
individually disposed on three or more legs projecting generally radially from the
base. Such stools are generally described in US patent
US 3312437 and in US patent application publication
US 2013/0320727.
[0004] The conventional stools typically assume an upright normal position when unoccupied.
The upright position is obtained by a resetting force which acts on the stool when
tilted out of its normal upright position. The resetting force is caused by coordinating
the center of gravity of the stool with the fixed shape of its base such that the
center of gravity assumes its lowest position when the stool is upright. Typically,
the resetting force is selected based on a desired characteristic of an unoccupied
stool.
[0005] The rounded base of conventional stools have several disadvantages: They may cause
noise when the stool is tilted, they require a relatively large and heavy base. The
base may slide or roll away due to a small contact surface with the floor, and the
stool generally provides insufficient support for a user when tilting out of the upright
position, making it undesirable or even dangerous in particular for elderly users.
[0006] Attempts have been made to address the inherent disadvantages of a fixedly formed
rounded base by using an inflatable base. An exemplary seating arrangement having
an inflatable rubber ring is disclosed in
US Patent 6,644,742. The inflatable base requires occasional reinflation, which is not practical. It
may also be prone to outgassing and cause an undesirable odor. A seat adapted to be
mounted on a vehicle tire is disclosed in
US 4,099,771 A1. The seat comprises a seat member, a seat base plate, a sleeve and a rod assembly,
and a nut and bolt assembly. A furniture construction wherein articles of furniture
are formed from discarded tires is disclosed in
US 5,338,097 A1.
[0007] Also, bases made of foam have been proposed, but those do not address the lack of
support for a user to maintain a generally upright seating position and do not adjust
to a user's weight.
SUMMARY
[0008] An improved tiltable stool provides soft and comfortable dynamic seating without
jeopardizing safety and stability. The stool is intended to be used while keeping
both of a user's feet on the ground. When tilted out of a normal position the stool
provides a stabilizing force which aides in maintaining a stable seating position.
The stabilizing force of the stool increases approximately exponentially with the
tilt angle of the stool out of the normal, typically upright, position. The stabilizing
force also increases with the weight of a user. At a given tilt angle the stabilizing
force increases approximately linearly with the weight of the user, thus making the
stool self-adjust to the user's weight. The improved stool provides a similar seating
experience for both light and heavy users: All users can easily tilt out of the normal
position, while experiencing a stabilizing force with increasing tilt angle that corresponds
to the user's weight. The improved tiltable stool provides dynamic seating flexibility
similar to that of an exercise ball, but eliminates the inherent instability of sitting
on a ball. Exercise balls have been associated with severe injuries when users have
lost their balanced and fallen over backward. When the stool is unoccupied the stabilizing
force is small and affected only by the weight of the stool, but sufficient to return
a tilted stool into a normal position.
[0009] The improved stool comprises a seat, a body structure, and a base. The base comprises
an annular elastic base member having a downwardly convex outer surface and a downwardly
concave inner surface. The annular elastic base member is held in a base structure.
The body structure extends between the seat and the base. Deformation of the annular
elastic base causes a stabilizing force which pushes the tiltable stool towards a
normal position when the tiltable stool or chair is tilted out of the normal position.
An upper section of the annular elastic base is substantially cylindrical and firmly
connected to the base structure. The downwardly convex outer surface of a lower section
of the annular elastic base member rests on the floor. When the stool is upright a
contact area between the annular elastic base member and the floor is substantially
ring-shaped, and grows outwardly with an increasing weight placed on the seat.
[0010] According to one aspect of the invention, the annular elastic base member has a tapered
cross-sectional shape with downwardly decreasing thickness. Typically, the normal
position of the stool is upright. When the stool is upright the outer surface of an
upper section of the annular elastic base member is substantially vertical. However,
the normal position may also be selected such that the stool is biased out of the
upright position.
[0011] A tongue-and-groove connection may be used to connect the annular elastic base member
to the base structure. A circular tongue at the upper end of the annular elastic base
member engages a corresponding circular groove of the base structure. The annular
elastic base may be press-fitted, glued, welded, or mechanically fixed to the base
structure. In particular, an electrically conductive disc may be disposed within the
circular groove of the base structure. The annular elastic base member may be welded
to the base structure by applying an electric current through the electrically conductive
disc. Alternatively, the tongue of the annular elastic base may be inserted into the
circular groove of the base structure by cooling the annular elastic base to reduce
the width of the circular tongue.
[0012] The annular elastic base may be made of various elastic materials, and is preferably
made of plastic, which may be reinforced by glass fibers. In particular, the annular
elastic base may be made of thermoplastic polyurethane (TPU).
[0013] According to another aspect of the invention the stool comprises an annular elastic
base having an outwardly convex, substantially "j"-shaped cross section. Deformation
of the annular elastic base affects a stabilizing force which increases with a tilt
angle between a tilted seating position and the upright position. The stabilizing
force increases approximately exponentially with the tilt angle. The stabilizing force
increases, preferably linearly, with a weight that is applied to the seat.
[0014] According to still another aspect of the invention the annular elastic base has a
substantially "o"-shaped cross section. The annular elastic base may then comprise
a pressurized cavity between an outer wall and an inner wall.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
FIG. 1 is a perspective top view of an exemplary tiltable stool.
FIG. 2 is a perspective bottom view of the stool as in FIG. 1.
FIG.3 is a cross sectional view of an exemplary tiltable stool, showing the stool
in a tilted position.
FIG. 4 is a detailed cross sectional view of an exemplary annular elastic base under
various loads.
FIG. 5 shows diagrams illustrating the relationship between load and deformation of
the annular elastic base and between tilt angle and stabilizing force.
FIG. 6 is a cross sectional view of an alternative profile of an annular elastic base
under two selected loads.
FIG. 7 shows a "j" profile of an annular elastic base under various loads.
FIG. 8 shows an "o" profile of an annular elastic base under various loads.
FIG. 9 shows exemplary contact areas of the annular elastic base with the floor under
various loads.
FIG. 10 is a cross section view through an exemplary annular elastic base in a normal
(upright) position and in a tilted position.
FIG. 11 is a perspective bottom view of an exemplary annular elastic base with additional
ridges.
FIG. 12 is a perspective bottom view of an exemplary annular elastic base in a tilted
position.
DETAILED DESCRIPTION
[0016] Referring to FIGS 1, 2 and 3, a tiltable stool
1 comprises a seat
2, a base
3, and an elongated body structure
4 between the base
3 and the seat
2. The stool
1 may comprise a height adjustment mechanism including an adjustment lever
7 to adjust the length of the body structure
4. The body structure
4 may comprise a pillar assembly and defines a vertical axis
13 of the stool
1.
[0017] The base
3 may comprising a base structure
6 connected to an annular elastic base member
5. The annular elastic base member
5 is configured to rest on the floor
14. The stool
1 is tiltable in any direction by deforming the annular elastic base member
5. When a tilting force is applied to the seat, the seat is moved from a normal position
into a dynamic seating position. Typically, the normal position is upright. In the
upright position the vertical axis
13 of the stool
1 is perpendicular to the floor
14. In response to a tilting force the annular elastic base member
5 is deformed, and the vertical axis
13 of the stool
1 is tilted by a tilt angle α out of the normal position. The annular elastic base
member
5 may be rotationally symmetrical and extend around a central opening
[0018] FIG. 3 shows a cross section of the stool
1 in a tilted seating position. Here, the stool
1 is tilted to the right by a tilt angle α out of the upright position. The annular
elastic base member
5 is deformed and the height of the annular elastic base varies. As shown, the annular
elastic base member
5 is compressed in the direction of the tilt (right side of FIG. 3) and expanded opposite
the direction of the tilt (left side of FIG. 3). Compression of the annular elastic
base member
5 causes a stabilizing force Fs at the seat
2 which counteracts the tilting force. In a stable tilted position the weight of the
user Fw is countered by an axial force Fa in the direction of the vertical axis
13 and the stabilizing force Fs which is perpendicular to the axial force Fa.
[0019] The annular elastic base member
5 extends from a substantially circular upper end
38 to a lower end
39 around an opening. The diameter of the annular elastic base member
5 at the upper end
38 is larger than the diameter of the annular elastic base member
5 at the lower end
39. Beneficially, the diameter at the upper end
38 is between approximately 1.2 and 1.6 times that of the diameter at the lower end
39. The annular elastic base member
5 has a downwardly convex outer surface
10 and a downwardly concave inner surface
11. The outer surface
10 of the annular elastic base contacts the floor
14 at a contact area
15. The contact area
15 extends at a distance around the vertical axis
13. A tongue
36 may be formed at the upper end
38 of the annular elastic base member
5 which engages a corresponding groove
37 in the base structure
6 to firmly connect the annular elastic base member
5 to the base structure
6.
[0020] FIG. 4 shows the deformation of an exemplary annular elastic base member
5 under various loads in more detail. When a first force F1 of approximately 400N/m
is applied, the annular elastic base member
5 has a first height
h1 and a first cross sectional shape
311. The first force F1 correlates to a person weighing about 40 kg sitting on a stool
to which an annular elastic base member with a diameter of 320 mm is attached. As
the stool is more heavily loaded, the annular elastic base member
5 is deformed. When loaded with a second force F2 of approximately 800N/m, corresponding
to a person with a weight of 80 kg sitting on the stool, the annular elastic base
member assumes a second cross sectional shape
312. The height of the annular elastic base is reduced by a first deformation
d2 to a second height
h2. When further loaded with a third force F3 of approximately 1200N/m, corresponding
to a person with a weight of about 120kg sitting on the stool, the annular elastic
base member
5 assumes a third cross sectional shape
313. Under the third load F3 the height of the annular elastic base is reduced by a second
deformation
d3 to a third deformed height
h3.
[0021] The relationship between deformation
d and load
F of an annular elastic base is generally shown in FIG. 5. The relationship
500 between deformation
d and load
F is non-linear. More specifically, with increasing deformation
d the load
F grows approximately exponentially. The non-linear relationship between load
F and deformation
d allows users of vastly different weight to use a stool equipped with the annular
elastic base, without significantly affecting the overall height of the stool.
[0022] Tilting a stool by an angle α out of the normal position causes a stabilizing force
opposite the direction of tilt. The relationship between tilt angle α and stabilizing
force Fr is generally shown in curves
501, 502 and
503 shown in FIG. 5. As illustrated, the stabilizing force is zero when the stool is
in an upright position, allowing a user to easily tilt. The stabilizing force Fr increases
with increasing tilt angle α as shown in curves
501, 502 and
503. The different curves show the stabilizing force for users of different weight. As
shown, the first curve
501 illustrates the stabilizing force for a heavy user weighing 120 kg. The second curve
502 illustrates the stabilizing force for a medium user weighing 80 kg. The third curve
503 illustrates the stabilizing force for a light user weighing 40 kg. At a given tilt
angle α' the stabilizing force F
r1 experience by the heavy user is larger than the stabilizing force F
r2 experienced by the medium user, which in turn is larger than the stabilizing force
F
r3 experienced by the light user. This desired effect provides a similar seating experience
for users of various weights. It provides additional stabilizing support for heavier
users without impeding the ability of lighter users to reach the same tilt angle.
[0023] FIG. 6 shows an alternative cross sectional shape
601, 602 of the annular elastic base member
5 in an unloaded state and in a loaded state. The annular elastic base member
5 preferably has an inwardly curved cross sectional shape
601, 602. The annular elastic base member
5 may be tapered, having a downwardly decreasing thickness. The thickness of the annular
elastic base member
5 may decrease from a first thickness
t1 at an upper, substantially cylindrical section
325 of the annular elastic base member
5 to a lower thickness
t2 at a lower end section
326 of the annular elastic base member
5. The tapered profile of the annular elastic base member
5 supports the desired load /deformation characteristic as shown in FIG. 5. Thinner
portions of the annular elastic
base member
5 close to its lower end
39 bend more easily than upper portions close to its upper end
38.
[0024] The uneven thickness of the annular elastic base member
5 allows a stool equipped therewith to be used equally by a very light user, such as
a child, and a heavy adult. In case of a child, only the lower, thinner, portions
of the annular elastic base member
5 will bend. When used by an adult, the thicker, upper, portions of the annular elastic
base member
5 will also bend. In both cases the user will experience a similar "feel" of the stool's
stabilizing force.
[0025] Under extreme load the lower end
39 of the annular elastic base member
5 may bend through completely and come to rest against the base structure
6. This limits the maximum deformation of and prevents damage to the annular elastic
base member
5 when exposed to extreme loads.
[0026] The annular elastic base member
5 may be shaped outwardly convex and inwardly concave. The downwardly convex outer
surface
10 and a downwardly concave inner surface
11 meet at the lower end
39 of the annular elastic base member. The lower end
39 of the annular elastic base member may extend into a stiffening ring
40 as shown in FIG. 4. The stiffening ring
40 at the lower end
39 helps stabilizes the annular elastic base member
5 at the contact area
15. The stiffening ring
40 protects the lower end
39 from kinking when the stool
1 is loaded and/or tilted out of its normal position. The stiffening ring
40 is preferably an integral component of the annular elastic base member
5.
[0027] To prevent kinking, the lower end
39 of the annular elastic base member
5 may also be bent upwardly, such that the contact area
15 between the annular elastic base member
5 and the floor is below and radially outward of the lower end
39 of the annular elastic base member
5.
[0028] When a stiffening ring
40 is used to strengthen the lower end
39 of the annular elastic base member
5, the unloaded annular elastic base
5 may contact the floor at the stiffening ring
40 as is shown in FIG. 4. This arrangement has been found beneficial when working with
relatively thick material. When using relatively thinner cross sectional shapes it
has been found beneficial to provide the unloaded contact area
15 of the annular elastic base
5 radially outwardly and below the stiffening ring
40 as is shown in FIG. 10.
[0029] Opposite the lower end
39 an upper end
38 of the annular elastic base member
5 may be formed as a tongue
36 which engages a corresponding groove
37 in the base structure
6. The tongue
36 may be slightly wider than the groove
37 and during assembly the tongue
36 may be press-fitted into the groove
37 with the help of a tool that secures the annular elastic base member
5 during insertion into the base structure
6. The tongue may be further secured with self-tapping screws. As shown in FIG. 11,
mounting holes
12 may be provided and are preferably circumferentially spaced at the base structure
6 to secure radially outwardly directed screws into an upper portion of the inner surface
11 of the annular elastic base member
5.
[0030] Alternatively, the tongue
36 of the annular elastic base member
5 may be assembled to the groove
37 of the base structure
6 by gluing or welding. In particular, the annular elastic base member
5 may be ultrasonically welded to the base structure
6. Welding may also be achieved by inserting an electrically conductive disc into the
groove
37 or by molding an electrically conductive element into the tongue
36. An electric current may then be applied to the electrically conductive disc in order
to cause resistive heating. The electric heating causes the surface of the tongue
36 to meld and weld to groove
37.
[0031] Yet another assembly option is to cool the annular elastic base member
5 to a temperature significantly below room temperature, causing the tongue
36 to shrink. Cooling may for example be affected by directing a cold gas onto the tongue
36 just before insertion into the groove
37. The groove
37 may be dimensioned such that the cooled tongue
36 can be easily inserted thereto, but is firmly held within the groove
37 once the tongue
36 warms back up to room temperature, expanding within the groove
37. Experiments have shown that load on the stool
1 reinforces the tongue-and-groove connection between the annular elastic base member
5 and the base structure
6, so that reinforcement of the connection by welding or gluing is not critical and
may not be necessary at all.
[0032] The cross-sectional profile and the material of the annular elastic base member
5 are coordinated to provide a desired seating experience. The annular elastic base
member
5 may be made of thermoplastic polyurethane (TPU), rubber, thermoplastic polyolefin
(TPO), fiberglass enforced polyamide (PA) or fiberglass enforced polyurethane (PU).
The selection of material requires a trade-off decision between cost and functionality.
Experiments including durability tests have shown, that a thermoplastic polyurethane
with 90 Shore hardness provides the required robustness at an affordable price. An
annular elastic base member
5 made of softer TPU with 75 Shore hardness would require about twice the amount of
material as one made of TPU with 90 Shore hardness.
[0033] The following configuration of the annular elastic base member
5 has been found to be particularly beneficial for users having a weight between 40
kg and 150 kg, which is a typical market requirement:
- Material: TPU
- Mass: 600 grams
- Hardness: 90 Shore
- Diameter at the upper end 38: 333 mm
- Diameter at the lower end 39: 245 mm
- Height h1 without load: 56mm (including the tongue 36)
- Height without load: 48mm (not including tongue 36)
- Tongue 36 dimensions: 8x8 mm
- Thickness t1 at an upper section 325: 13 mm
- Thickness t2 at a lower section 326: 2 mm
- Thickness (diameter) of the stiffening ring 40: 8 mm
[0034] An alternative substantially "j"-shaped cross-sectional profile
701, 702, 703 of an annular elastic base member
5 under three different loads is shown in FIG. 7. This profile may be used in combination
with harder materials such as fiber-enforced polyamide or polypropylene. The shown
"j"-shaped profile
701, 702, 703 has a more even thickness and consequently bends more readily compared to the tapered
profile
601 shown in FIG. 6. While this is generally not preferred as it increases the risk of
kinking, the "j"-shaped profile
701, 702, 703 may be manufactured more cost effectively, and may hence be a viable alternative
for cost sensitive products.
[0035] Yet another alternative cross-sectional profile
801, 802, 803 is substantially "o"-shaped as shown in FIG. 8. An annular elastic base member
5 having a substantially "o"-shaped cross-sectional profile
801 may be manufactured by extrusion, and thus be an alternative to molded profiles.
Alternatively, the annular elastic base member
5 having a substantially "o"-shaped cross-sectional profile
801 may be formed by rotational molding or by blow molding. The substantially "o"-shaped
profile
801 may comprise a cavity
804 which may be filled with air or another gas and may be pressurized.
[0036] FIG. 9 illustrates the shape of the contact area
15 of the annular elastic base
5 with the floor
14 under various loads. An unloaded stool may have a contact area
15 that assumes a first circular shape
331. For reference, the position
335 of the upper end
38 of the annular elastic base member
5 is shown in a dashed line in FIG.9. When the stool is symmetrically loaded and upright
the contact area grows outwardly but remains circular. Consequently, the contact area
15 may assume a second circular shape
332 that has larger diameter than the first circular shape
331 when additional weight is placed on the stool. When tilted, the contact area may
assume a substantially oval shape
333. As shown, the substantially oval shaped contact area
333 has a longer inner lever l
i than outer lever l
o. The inner level l
i is measured from the intersection of the vertical axis
13 with the floor
14 to the contact area in the direction of the tilt. The outer lever l
o is measured from the intersection of the vertical axis
13 with the floor
14 to the contact area in the direction opposite the tilt. The contact area
15 remains within the confines of the position
335 of the upper end
38 of the annular elastic base member
5 under all loads, and whether loaded symmetrically or asymmetrically.
[0037] When the an annular elastic base member
5 is used with additional circumferentially spaced radially extending ridges
42, the contact area
15 consists of a plurality of circumferentially spaced radially extending surfaces
336 that are arranged in an approximately circular shape
331, 332 or approximately oval shape
333 as explained above.
[0038] The stool may be tilted beyond its dynamic seating envelope of about 10 degrees.
In that case the substantially oval shaped contact area
333 opens up at the inner end and eventually assumes an approximately crescent-shape
334. When tilting the stool beyond its dynamic seating envelope a user will remain a stable
position by applying force to his legs. Advantageously, the so tilted stool does not
have a tendency to roll sideways. Further, the elasticity of the annular elastic base
provides good friction on the floor and thus prevents the stool from sliding backward.
[0039] When in its upright position the annular elastic base member
5 has a substantially ring-shaped, circular, contact area
15 with the floor. Increasing deformation of the annular elastic base member
5 causes the diameter of this ring-shaped contact area
15 to grow outwardly. This increases the effective lever arm 1 of the annular elastic
base member
5. When the stool
1 is tilted out of its normal position the contact area
15 changes from a circular shape toward an approximately oval shape. Beneficially, the
effective inner lever l
i in the direction of the tilt is growing larger, while the effective outer lever l
o opposite the direction of tilt is getting smaller. This effect amplifies the stabilizing
force of the stool and contributes to its stability.
[0040] The shape of the contact area as shown in Fig. 9 is further illustrated in the cross
sectional view of Fig. 10. Here, the annular elastic base
5 is shown in a symmetrically loaded or upright position
8 and in a tilted position
9. In the tilted position
9 the annular elastic base member
5 is tilted by an angle α out of the upright position
8. The comparison of the symmetrically loaded upright position
8 with the tilted position
9 shows the relative change of the inner lever l
i and the outer lever l
o. As shown, the inner lever l
i grows in the direction of the tilt and the outer lever l
o becomes shorter in the direction opposite the tilt.
[0041] The maximum elastic deformation of the annular elastic base member
5 may allow spring-loaded tilt of the stool of up to about 10 degrees and be associated
with the equivalent of a symmetrical load of 200 kg. A user may tilt the stool beyond
its dynamic seating envelope up to about 45 degree. This is achieved by lifting the
backward portion of the annular elastic base member
5 into the air. Tilting the stool up to about 45 degrees allows a user to conveniently
pick up articles from the floor. The shape of the annular elastic base member as described
before provides a relatively smooth and seamless transition from dynamic deformation
(up to approximately 10 degrees) to lifting the backward portion of the base into
the air (between approximately 10 degrees and 45 degrees).
[0042] FIG. 11 shows an annular elastic base member
5 with additional circumferentially spaced radially extending ridges
42 at the contact area of the annular elastic base with the floor. The radially extending
ridges
42 have been found to prevent noise that might otherwise be caused by deformation of
the annular elastic base member
5. Noise may stem from vibrations that may be caused when the annular elastic base member
5 deforms while a user tilts the associated stool. The radially extending ridges
42 may also prevent a vacuum from forming under a stool equipped with the annular elastic
base member
5. This is particularly relevant if the annular elastic base member
5 and the base structure
6 form an upwardly sealed surface. In that case, the annular elastic base member
5 and the base structure
6 could act a large suction cup, which must be prevented. Prevention is achieved by
the ridges
42 which segment the contact area of the annular elastic base
5 with the floor
14 and allow air to pass through air channels between the ridges
42. Instead of ridges
42, grooves (not shown) may be applied to the annular elastic base member
5 in an equivalent circumferentially spaced and radially extending arrangement to provide
the desired air channels. FIG. 11 shows a configuration with 44 ridges. Alternative
configurations may choose to use more or fewer ridges, for example between 20 and
80 ridges.
[0043] Fig. 12 shows a deformed annular elastic base member
5 under extreme load. The lower end
39 of the annular elastic base member
5 here bends through completely and comes to rest against a stop surface
320 of the base structure
6. This limits the maximum deformation and thereby prevents damage of the annular elastic
base member
5 when exposed to extreme loads. The extremely loaded stool remains slighdy elastic
based on compression of the material of the annular elastic base
5. Damage to the floor is prevented as the base structure
6 does not contact the floor even under extreme load.
[0044] While the present invention has been described with reference to exemplary embodiments,
it will be readily apparent to those skilled in the art that the invention is not
limited to the disclosed or illustrated embodiments but, on the contrary, is intended
to cover numerous other modifications, substitutions, variations and broad equivalent
arrangements that are included within the scope of the following claims. For example,
while this specification and the claims refer to a stool, it should be understood
that the invention can equally be applied to a chair or other tiltable article of
furniture.
Alternative Examples
[0045] A tiltable stool, comprising:
a seat;
an annular elastic base member; and
an elongated body structure extending between the seat and the base.
[0046] The tiltable stool as above, wherein the annular elastic base is rotationally symmetrical.
[0047] The tiltable stool as above, wherein the annular elastic base member comprises a
downwardly convex outer surface and a downwardly concave inner surface extending around
a central opening.
[0048] The tiltable stool as above, further comprising a height adjustment mechanism.
[0049] The tiltable stool as above, wherein the elongated body structure comprises a pillar
assembly and defines a vertical axis of the stool.
[0050] The tiltable stool as above, wherein the annular elastic base member is an integral
molded component.
[0051] The tiltable stool as above, wherein the annular elastic base member rests on the
floor.
[0052] The stool as above, wherein the stool can be tilted in any direction by deforming
the annular elastic base.
[0053] The stool as above, wherein the stool can be tilted in any direction by deforming
the annular elastic base within a dynamic seating enveloped of approximately 10 degree
tilt.
[0054] The stool as above, wherein the stool can be tilted beyond the dynamic seating envelope
by lifting a backward portion of the annular elastic base into the air.
[0055] The stool as above, wherein the stool wherein the stool has an upright normal position.
[0056] The stool as above, wherein deformation and/or compression of the annular elastic
base member causes a stabilizing force.
[0057] The stool as above, wherein the stabilizing force increases with the weight of a
user.
[0058] The stool as above, wherein the stabilizing force increases with the tilt angle of
the stool.
[0059] The stool as above, wherein the stabilizing force increases approximately exponentially
with the tilt angle of the stool.
[0060] The stool as above, wherein the height of the annular elastic base member decreases
in the direction of tilt when the stool is tilted.
[0061] The stool as above, wherein the height of the annular elastic base member increases
in the direction opposite tilt when the stool is tilted.
[0062] The stool as above, wherein a tongue is formed at an upper end of the annular elastic
base member.
[0063] The stool as above, wherein the tongue engages a corresponding groove in the base.
[0064] The stool as above, wherein the tongue has a height of approximately 8 mm and a thickness
of approximately 8 mm.
[0065] The stool as above, wherein the tongue is press-fitted into the groove.
[0066] The stool as above, wherein the stool is configured to support a user having a weight
between 40 kg and 150 kg.
[0067] The stool as above, wherein the annular elastic base is configured to support a load
between approximately 400 N/m and 1500 N/m.
[0068] The stool as above, wherein the annular elastic base member has an inwardly curved
cross section.
[0069] The stool as above, wherein the annular elastic base member is tapered having a downwardly
decreasing thickness.
[0070] The stool as above, wherein the annular elastic base member is tapered having a downwardly
decreasing thickness.
[0071] The stool as above, wherein the annular elastic base member is made of thermoplastic
polyurethane.
[0072] The stool as above, wherein the annular elastic base member has a mass of approximately
600 grams.
[0073] The stool as above, wherein the annular elastic base member has a hardness of approximately
90 Shore.
[0074] The stool as above, wherein the annular elastic base member has a diameter at the
upper end of approximately 333 mm.
[0075] The stool as above, wherein the annular elastic base member has a diameter at the
lower end of approximately 245 mm.
[0076] The stool as above, wherein the annular elastic base member has a diameter at the
upper end that is approximately 1.4 times its diameter at the lower end.
[0077] The stool as above, wherein the annular elastic base member has a diameter at the
upper end that is between 1.2 and 1.6 times its diameter at the lower end.
[0078] The stool as above, wherein the annular elastic base member has height
h1 without load of approximately 56mm including a tongue.
[0079] The stool as above, wherein the annular elastic base member has height without load
of approximately 48mm, not including a tongue.
[0080] The stool as above, wherein the annular elastic base member has a thickness
t1 at its upper end of approximately 13 mm.
[0081] The stool as above, wherein the annular elastic base member has a thickness
t2 at its lower end of about 2 mm.
[0082] The stool as above, wherein a lower end of the annular elastic base member touches
a stop surface when fully deformed under heavy load.
[0083] The stool as above, wherein deformation of the annular elastic base is limited by
a stop surface in the base which supports the lower end of the annular elastic base
under heavy loads.
[0084] The stool as above, wherein the annular elastic base is secured to the base by screws.
[0085] The stool as above, wherein the annular elastic base is secured to the base by self-tapping
screws.
[0086] The stools as above, wherein mounting holes are provided and circumferentially spaced
at the base structure to secure radially outwardly directed screws into an upper portion
of the inner surface of the annular elastic base member.
[0087] The stools as above, wherein the lower end of the annular elastic base member is
bent upwardly, such that the contact area between the annular elastic base member
and the floor is below and radially outward of the lower end of the annular elastic
base member.
[0088] The stool as above, wherein a stiffening ring is provided at the lower end of the
annular elastic base member.
[0089] The stool as above, wherein the stiffening ring has a diameter of approximately 8
mm.
[0090] The stool as above, wherein the annular elastic base member contacts the floor at
the stiffening ring when the stool is unoccupied.
[0091] The stool as above, wherein the annular elastic base member contacts the floor radially
outwardly and axially below the stiffening ring when the stool is unoccupied.
[0092] The stool as above, wherein the annular elastic base member has an approximately
circular contact area with the floor when the stool is upright.
[0093] The stool as above, wherein the radius of the approximately circular contact area
with the floor increases as weight is placed onto the stool.
[0094] The stool as above, wherein the contact area of the annular elastic base member with
the floor is approximately oval when the stool is tilted.
[0095] The stool as above in a tilted position, wherein an outer lever l
o measured from the intersection of the vertical axis with the floor to the contact
area in the direction opposite the tilt is shorter than an inner lever l
i measured from the intersection of the vertical axis with the floor to the contact
area in the direction of the tilt.
[0096] The stool as above, further comprising circumferentially spaced radially extending
ridges at the contact area of the annular elastic base with the floor.
[0097] The stool as above, comprising between 20 and 80 ridges.
[0098] The stool as above, further comprising circumferentially spaced radially extending
grooves at the contact area of the annular elastic base with the floor.
[0099] The stool as above, comprising between 20 and 80 grooves.
1. Kippbarer Hocker (1), umfassend:
einen Sitz (2);
eine Basis (3), die ein ringförmiges elastisches Basiselement (5) umfasst;
eine Körperstruktur (4), die sich zwischen dem Sitz (2) und der Basis (3) erstreckt,
wobei das ringförmige elastische Basiselement (5) eine konische Querschnittsform mit
nach unten abnehmender Dicke aufweist und
wobei die Verformung des ringförmigen elastischen Basiselements (5) eine Stabilisierungskraft
bewirkt, die den kippbaren Hocker (1) in eine normale Position drückt, wenn der kippbare
Hocker (1) aus der normalen Position herausgekippt wird, wobei
wobei das elastische Basiselement (5) eine nach unten konvexe Außenfläche (10) und
eine nach unten konkave Innenfläche (11) aufweist, dadurch gekennzeichnet, dass
die Stabilisierungskraft (Fs) mit dem Neigungswinkel (α) ungefähr exponentiell zunimmt.
2. Kippbarer Hocker (1) nach Anspruch 1, wobei die Basis (3) ferner eine Basisstruktur
(6) umfasst, und wobei ein oberer Abschnitt des ringförmigen elastischen Basiselements
(5) im Wesentlichen zylindrisch ist und fest mit der Basisstruktur (6) verbunden ist.
3. Kippbarer Hocker (1) nach Anspruch 1 oder 2, wobei ein unteres Ende des ringförmigen
elastischen Basiselements (5) die Basisstruktur (6) berührt, wenn das ringförmige
elastische Basiselement (5) vollständig verformt ist.
4. Kippbarer Hocker (1) nach Anspruch 1, 2 oder 3, wobei die nach unten konvexe Außenfläche
(10) eines unteren Abschnitts des ringförmigen elastischen Basiselements (5) auf dem
Boden (14) aufliegt.
5. Kippbarer Hocker (1) nach Anspruch 4, wobei eine Kontaktfläche (15) zwischen dem ringförmigen
elastischen Basiselement (5) und dem Boden (14) im Wesentlichen ringförmig ist, und
wobei die Kontaktfläche (15) nach außen wächst, wenn ein Gewicht auf den Sitz platziert
wird.
6. Kippbarer Hocker (1) nach Anspruch 1, wobei das ringförmige elastische Basiselement
(5) an seinem oberen Ende eine kreisförmige Feder (36) aufweist, die in eine entsprechende
kreisförmige Nut (37) einer Basisstruktur (6) eingreift.
7. Kippbarer Hocker (1) nach Anspruch 6, wobei die kreisförmige Feder (36) in die entsprechende
kreisförmige Nut (37) eingepresst ist.
8. Kippbarer Hocker (1), umfassend:
einen Sitz (2);
eine Basis (3), die ein rotationssymmetrisches ringförmiges elastisches Basiselement
(5) umfasst; und
eine längliche Körperstruktur (4), die sich zwischen dem Sitz (2) und der Basis (3)
erstreckt,
wobei die Verformung des ringförmigen elastischen Basiselements (5) eine Stabilisierungskraft
(FS)bewirkt, die den kippbaren Hocker (1) in eine normale Position drückt, wenn der kippbare
Hocker (1) aus der normalen Position herausgekippt wird, wobei
das elastische Basiselement (5) einen nach außen konvexen, im Wesentlichen "j"-förmigen
Querschnitt (701, 702, 703) oder einen im Wesentlichen o-förmigen Querschnitt (801,
802, 803) mit einer nach unten konvexen Außenfläche und einer nach unten konkaven
Innenfläche umfasst, die sich um eine zentrale Öffnung erstreckt, dadurch gekennzeichnet, dass die Stabilisierungskraft (FS) mit dem Neigungswinkel (α) ungefähr exponentiell zunimmt.
9. Kippbarer Hocker (1) nach Anspruch 1 oder 8, wobei das ringförmige elastische Basiselement
(5) eine Vielzahl von in Umfangsrichtung beabstandeten und sich radial erstreckenden
Nuten oder Kanten (42) in einer Kontaktfläche (15) mit dem Boden (14) umfasst.
10. Kippbarer Hocker (1) nach einem der Ansprüche 1 bis 9, wobei der kippbare Hocker (1)
eine im Wesentlichen aufrechte Position aufweist, wenn er nicht einer Kippkraft ausgesetzt
ist, und wobei der kippbare Hocker (1) durch eine Kippkraft von der aufrechten Position
in eine dynamische Sitzposition weggekippt werden kann, und wobei die Verformung des
ringförmigen elastischen Basiselements (5) eine Stabilisierungskraft (FS) bewirkt, die den kippbaren Hocker (1) gegen die Kippkraft aus der dynamischen Sitzposition
in die aufrechte Position drückt.
11. Kippbarer Hocker (1) nach einem der Ansprüche 1 bis 10, wobei die Stabilisierungskraft
(FS) mit einem Neigungswinkel (α) zwischen der dynamischen Sitzposition und der aufrechten
Position zunimmt.
12. Kippbarer Hocker (1) nach einem der Ansprüche 1 bis 10, wobei die Stabilisierungskraft
(FS) mit einem Gewicht zunimmt, das auf den Sitz (2) aufgebracht wird.
13. Kippbarer Hocker nach einem der Ansprüche 1 bis 10, wobei das ringförmige elastische
Basiselement (5) konisch ist und eine nach unten abnehmende Dicke von ungefähr 13
mm an einem oberen Ende und von ungefähr 2 mm an einem unteren Ende aufweist, und
wobei das ringförmige elastische Basiselement (5) aus thermoplastischem Polyurethan
mit einer Härte von ungefähr 90 Shore hergestellt ist, und wobei das obere Ende des
ringförmigen elastischen Basiselements (5) einen Durchmesser von ungefähr 333 mm aufweist,
und wobei das untere Ende des ringförmigen elastischen Basiselements (5) einen Durchmesser
von ungefähr 245 mm aufweist, und wobei ein Versteifungsring (40) mit einer Dicke
von ungefähr 8 mm am unteren Ende des ringförmigen elastischen Basiselements (5) vorgesehen
ist.
14. Kippbarer Hocker (1) nach einem der Ansprüche 1 bis 13, wobei das ringförmige elastische
Basiselement (5) am oberen Ende einen Durchmesser aufweist, der zwischen dem 1,2-
und 1,6-fachen seines Durchmessers am unteren Ende liegt, wenn sich der kippbare Hocker
in einem unbelasteten Zustand befindet.
1. Tabouret inclinable (1), comportant :
un siège (2) ;
une embase (3) qui comprend un élément de base (5) élastique de forme annulaire ;
une structure de corps (4) qui s'étend entre le siège (2) et l'embase (3), dans lequel
l'élément de base (5) élastique de forme annulaire présente en section transversale
une forme conique ayant une épaisseur qui diminue vers le bas, et
la déformation de l'élément de base (5) élastique en forme annulaire engendre une
force de stabilisation qui pousse le tabouret inclinable (1) jusque dans une position
normale lorsque le tabouret inclinable (1) est incliné hors de la position normale,
et
l'élément de base (5) élastique présente une surface extérieure (10) convexe vers
le bas et une surface intérieure (11) concave vers le bas,
caractérisé en ce que
la force de stabilisation (Fs) augmente approximativement exponentiellement au fur
et à mesure de l'angle d'inclinaison (α).
2. Tabouret inclinable (1) selon la revendication 1, dans lequel l'embase (3) comprend
en outre une structure de base (6), et une portion supérieure de l'élément de base
(5) élastique en forme annulaire est sensiblement cylindrique et fermement reliée
à la structure de base (6).
3. Tabouret inclinable (1) selon la revendication 1 ou 2, dans lequel une extrémité inférieure
de l'élément de base (5) élastique en forme annulaire vient toucher la structure de
base (6) lorsque l'élément de base (5) élastique en forme annulaire est déformé complètement.
4. Tabouret inclinable (1) selon la revendication 1, 2 ou 3, dans lequel la surface extérieure
(10) convexe vers le bas d'une portion inférieure de l'élément de base (5) élastique
en forme annulaire repose sur le sol (14).
5. Tabouret inclinable (1) selon la revendication 4, dans lequel une surface de contact
(15) entre l'élément de base (5) élastique en forme annulaire et le sol (14) est sensiblement
annulaire, et la surface de contact (15) augmente vers l'extérieur lorsqu'un poids
est placé sur le siège.
6. Tabouret inclinable (1) selon la revendication 1, dans lequel l'élément de base (5)
élastique en forme annulaire comprend à son extrémité supérieure un ressort circulaire
(36) qui s'engage dans une gorge (37) circulaire correspondante d'une structure de
base (6).
7. Tabouret inclinable (1) selon la revendication 6, dans lequel le ressort circulaire
(36) est enfoncé dans la gorge (37) circulaire correspondante.
8. Tabouret inclinable (1), comportant :
un siège (2) ;
une embase (3) qui comprend un élément de base (5) élastique de forme annulaire à
symétrie de révolution ; et
une structure de corps (4) allongée qui s'étend entre le siège (2) et l'embase (3),
dans lequel
la déformation de l'élément de base (5) élastique en forme annulaire engendre une
force de stabilisation (FS) qui pousse le tabouret inclinable (1) jusque dans une position normale lorsque le
tabouret inclinable (1) est incliné hors de la position normale, et
l'élément de base (5) élastique présentant une section transversale (701, 702, 703)
convexe vers l'extérieur et sensiblement en forme de "j" ou une section transversale
(801, 802, 803) sensiblement en forme de "o" ayant une surface extérieure convexe
vers le bas et une surface intérieure concave vers le bas qui s'étend autour d'une
ouverture centrale,
caractérisé en ce que
la force de stabilisation (Fs) augmente approximativement exponentiellement au fur
et à mesure de l'angle d'inclinaison (α).
9. Tabouret inclinable (1) selon la revendication 1 ou 8, dans lequel l'élément de base
(5) élastique en forme annulaire comprend une multitude de gorges ou d'arêtes (42)
dans une surface de contact (15) avec le sol (14), qui sont espacées en direction
périphérique et qui s'étendent radialement.
10. Tabouret inclinable (1) selon l'une des revendications 1 à 9, dans lequel le tabouret
inclinable (1) présente une position sensiblement redressée lorsqu'il n'est pas soumis
à une force d'inclinaison, et le tabouret inclinable (1) peut être incliné depuis
la position redressée jusque dans une position d'assise dynamique par une force d'inclinaison,
et la déformation de l'élément de base (5) élastique en forme annulaire engendre une
force de stabilisation (FS) qui pousse le tabouret inclinable (1) depuis la position d'assise dynamique jusque
dans la position redressée à l'encontre de la force d'inclinaison.
11. Tabouret inclinable (1) selon l'une des revendications 1 à 10, dans lequel la force
de stabilisation (FS) augmente au fur et à mesure de l'angle d'inclinaison (α) entre la position d'assise
dynamique et la position redressée.
12. Tabouret inclinable (1) selon l'une des revendications 1 à 10, dans lequel la force
de stabilisation (FS) augmente au fur et à mesure d'un poids appliqué sur le siège (2).
13. Tabouret inclinable (1) selon l'une des revendications 1 à 10, dans lequel l'élément
de base (5) élastique en forme annulaire est conique et présente une épaisseur qui
diminue vers le bas et qui est d'environ 13 mm à une extrémité supérieure et d'environ
2 mm à une extrémité inférieure, et l'élément de base (5) élastique en forme annulaire
est réalisé en polyuréthane thermoplastique d'une dureté d'environ 90 Shore, et l'extrémité
supérieure de l'élément de base (5) élastique en forme annulaire présente un diamètre
d'environ 333 mm, et l'extrémité inférieure de l'élément de base (5) élastique en
forme annulaire présente un diamètre d'environ 245 mm, et il est prévu un anneau de
rigidification (40) ayant une épaisseur d'environ 8 mm à l'extrémité inférieure de
l'élément de base (5) élastique en forme annulaire.
14. Tabouret inclinable (1) selon l'une des revendications 1 à 13, dans lequel l'élément
de base (5) élastique en forme annulaire présente à l'extrémité supérieure un diamètre
qui est compris entre 1,2 fois et 1,6 fois son diamètre à l'extrémité inférieure lorsque
le tabouret inclinable est dans un état non chargé.